Device for use in making nodular cast iron



Feb. 3, 1959 P. A. FISHER 2,872,179

DEVICE FOR USE IN MAKING NODULAR CAST IRON Filed Jan. 25, 1957 wvvvvvvvInventor DEVICE FQR USE IN MAKING NODULAR CAST IRON Philip A. Fisher,Manchester, England, assignor t Magnesium Elektron Limited, Manchester,England Application January 23, 1957, Serial No. 635,725

Claims priority, application Great Britain January 23, 1956 3 Claims.(Cl. 26634) This invention relates to the introduction of avolatilisable metal into molten iron or steel especially for the purposeof producing nodular cast iron.

The production of nodular cast iron, has until fairly recently, beenmainly carried out by treatment with magnesium in the form of anickel-magnesium alloy. This is added to the normal ladles, the dilutionwith nickel being required to enable the magnesium to sink to the bottomof the ladle where it volatilises and passes through the iron. Thisprocess is expensive since the nickel content of the hardener is usually70-80% and the magnesium efiiciency (i. e. the portion of the magnesiumwhich is used effectively) may be only about 30%, the balance beingmainly lost by oxidation of magnesium vapour which is ejected from themolten iron.

Recently a number of devices have been developed to permit the use ofpure magnesium and one of these is known as a pressure ladle apparatus.In this device the magnesium is plunged below the surface of the molteniron which is held in a sealed ladle, thus preventing the loss ofmagnesium to the atmosphere. Magnesium recoveries are about 40-60%, themajor saving in cost being avoidance of nickel consumption. In itsoriginal form the device includes a specially shaped ladle above whichis suspended a refractory coated plunger incorporating a sealing plateand a heavy weight to maintain the pressure generated by the vapourisedmagnesium. At the bottom of the plunger is attached a steel canisterinto which is packed loose pieces of pure magnesium. In operation theladle is filled with molten iron and the plunger lowered into this untilthe sealing plate closes the top of the ladle. For each operation thejoint between sealing plate and ladle has to be specially prepared usingsome form of sealing compound, and some little time, say up to 30seconds, may be required to accomplish this. It is therefore essentialthat the magnesium should not commence to volatilise before this jointis completed.

As a further development, a solid magnesium billet containing aprojecting steel rod has been used. This billet is first coated withrefractory to provide the necessary delay before volatilisation and thebillet is then attached to the plunger by threading the steel rod into ascrew at the end of the plunger.

According to the present invention a method of producing nodular castiron comprises introducing a readily volatilisable metal into molteniron by means of a plunger comprising a billet of metal consisting of orcontaining the volatilisable metal having its top and sides sheathed iniron or steel, the plunger being mounted on a holder. The base of thebillet may be coated with reatent O 2,872,179 Patented Feb. 3, 1959fractory. The billet may be pure magnesium or an alloy e. g. a magnesiumalloy containing aluminium or rare earth metals, or may be rare earthmetals alone. Additional means may be provided to hold the billet inposition within the steel sheath, to prevent solid metal from leavingthe sheath during the period in which this is immersed in the iron.

A plunger made in accordance with the invention is illustrated by way ofexample in the accompanying diagrammatic drawing wherein 10 shows a mildsteel tube having one end closed by a plate 11 welded thereon. The plate11 has a stud 13 welded to it. A threaded bolt 14 passes through thestud 13 and is disposed in the tube and carries a washer 15 in the tube.The volatilisable metal 12 is cast into the tube around the bolt 14 andwasher 15. The metal 12 is thus in the form of a billet and is sheathedat its sides by the tube 10 and at its top by the plate 11. Theunsheathed lower end 16 of the billet may be coated with a refractorymaterial.

The washer 15 serves as a means of anchoring the magnesium and otheranchorage means may be provided attached to the stud and/or to thesheathing.

The end 16 can if desired be also covered by a welded on steel plate.

The upper end of the stud 16 is threaded for attach ment to a rod orhandle.

The invention offers the following advantages:

(1) The magnesium or the like tends to volatilise from the open end onlywhereby the magnesium vapour travels by the longest path through thecast iron, thereby giving the greatest possibility of satisfactoryreaction.

(2) The exposed area of magnesium, which may be coated with refractory,is minimised, whereby the device is safer in operation than the use of abillet in which the whole surface is so coated.

(3) In the event of premature volatilisation any explosion which mightresult is directed downwards thus minimising the risk of accident.

The refractory may be applied for example by coating the exposedmagnesium with a synthetic resin and dipping it in sand.

I claim:

1. A device for use in making nodular cast iron, comprising a plunger inthe form of a tube of ferrous metal having its lower end open and itsupper end enclosed, said tube containing a billet of solid metal readilyvolatilizable in molten iron and suitable for treatment of iron, thetube having a rod extending through said closed upper end, the upper endof said rod being attached to a holder, the lower portion of said rodhaving means, rigidly attached thereto, embedded in said billet of solidmetal to anchor the same within said tube.

2. A device as set forth in claim 1, wherein said solid metal ismagnesium.

3. A device as set forth in claim 1 wherein the solid metal adjacent thelower end of the tube is coated with a refractory material.

References Cited in the file of this patent UNITED STATES PATENTS1,896,201 Sterner-Rainer Feb. 7, 1933 2,485,760 Millis et al. Oct. 25,1949 2,662,008 Stone Dec. 8, 1953 2,726,152 Eash Dec. 6, 1955

1. A DEVICE FOR USE IN MAKING NODULAR CAST IRON, COMPRISING A PLONGER IN THE FORM OF A TUBE OF FERROUS METAL HAVING ITS LOWER END OPEN AND ITS UPPER END ENCLOSED, SAID TUBE CONTAINING A BRILLET OF SOLID METAL READILY VOLATILIZABLE IN MOLTEN IRON AND SUITABLE FOR TREATMENT OF IRON, THE TUBE HAVING A ROD EXTENDING THROUGH SAID CLOSED UPPER END, THE UPPER END OF SAID ROD BEING ATTACHED TO A HOLDER, THE LOWER PORTION OF SAID ROD HAVING MEANS, IGIDLY ATTACHED THERETO, EMBEDDED IN SAID BILLET OF SOLID METAL TO ANCHOR THE SAME WITHIN SAID TUBE. 